Methotrexate-associated toxicity in children with Down syndrome and acute lymphoblastic leukemia during consolidation therapy with high dose methotrexate according to ALL-BFM treatment regimen.

ABSTRACT

Children with Down syndrome (DS) and acute lymphoblastic leukemia (ALL) often suffer from severe toxicities during treatment, especially with high-dose methotrexate (HD-MTX). Systematic data on methotrexate (MTX) toxicity in these patients are rare. We analyzed seven MTX-associated toxicities during consolidation therapy in 103 DS- and 1,109 non-DS-patients (NDS) with ALL (NDS-ALL) enrolled in ALL-Berlin-Frankfurt-Münster (ALL-BFM) trials between 1995-2016 and 1995-2007, respectively. Patients received four courses MTX (5 g/m2 each) plus intrathecal MTX and 6-mercaptopurine (6-MP). From 2004 onwards, a dose of 0.5 g/m2 in the first MTX course has been recommended for DS-patients. DS-patients showed higher rates of grade 3/4 toxicities after the first course with 5 g/m2 MTX compared to NDS-patients (grade 3/4 toxicities 62 in 45 DS-patients vs 516 in 1,089 NDS-patients, P<0.001). The dose reduction (0.5 g/m2) in DS-patients has reduced toxicity (39 in 51 patients, P<0.001) without increasing the relapse risk (reduced dose, 5-year cumulative relapse incidence = 0.09±0.04 vs high dose, 0.10±0.05, P=0.51). MTX dose escalation to 1.0 g/m2 for DS-patients who tolerated 0.5 g/m2 (n= 28 of 51 patients) did not result in an increased rate of grade 3/4 toxicities after the second course (P=0.285). Differences in MTX plasma levels at 42 and 48 hours after the start of the first methotrexate infusion did not explain higher toxicity rates in DS-patients treated with 0.5 g/m2 compared to NDS-patients treated with 5 g/m2 Within the DS cohort a higher MTX plasma level was associated with increased toxicity. In conclusion, dose reduction in the first MTX course reduced severe toxicities without increasing the risk of relapse. (ClinicalTrials.gov identifier NTC00430118, NCT01117441).